Researchers are stopping a study testing a daily pill to prevent infection with the AIDS virus in thousands of African women.
Partial results show that women taking Truvada, made by Gilead Sciences Inc., are just as likely to get HIV as other women who take dummy pills.
Even if the study continues, it will not be able to determine whether the pills do any good. The results are a disappointment because a study last fall found that Truvada did help prevent infections in gay and bisexual men, and many AIDS experts view it as a breakthrough.
The new study's results were announced on Monday.